Phylogeny and taxonomy of powdery mildew on species.

The phylogeny and taxonomy of powdery mildew on species is evaluated and discussed. Morphological and phylogenetic analyses revealed two new species and demonstrated that and should be reduced to synonymy and are referred to herein as . The two new species, and , previously hidden under (including ), is described on the basis of European, North American, and East Asian powdery mildew collections on var. , and . The sexual morph of is similar to that of ; however, morphological differences exist in their asexual morphs. Analyses of sequences from the internal transcribed spacer (ITS) and 28S genomic regions of species obtained on species (and other closely allied species) throughout the world reveled that and are in two different monophyletic groups that are separate from all other species. and on species have often been recognized as separate species based on morphological differences in the size of their chasmothecia and the number of chasmothecial appendages. Taxonomic conclusions based on these morphological distinctions within these species are unreliable (these characters are rather variable and often have overlapping ranges). The present phylogenetic analyses suggest that has to be reduced to synonymy with . To fix the application of the species names and , epitypes have been designated for these taxa with ex-epitype sequences. Additionally, the Asian species is phylogenetically confirmed as a species of its own, described in detail and discussed.